import java.util.Arrays;
public class Test1 {
    public static  void transform(int[] arr){
        if(arr==null){
            return;
        }
        for (int i = 0; i <arr.length; i++) {
            arr[i]*=2;
        }
    }

    public static void main(String[] args) {
        int[] arr1={1,2,3};
        transform(arr1);
        System.out.println(Arrays.toString(arr1));
    }
}
